The invention relates to a flame protection device for gas bags in airbag modules.
It is known that darts (the joining of two pieces) are often provided in gas bags of airbag modules in order to restrict the expansion of the gas bag. When these darts are located directly adjoining the gas generator they are heavily stressed thermally by the hot gas jet.
It is known to protect heavily thermally stressed parts of the gas bag by attaching additional parts as flame protection to protect the thermally stressed parts against the impact of the hot gases. Thus, an airbag is known from German Patent DE 41 21 659 C2 where a gas generator cover is attached over the gas generator. This cover is to prevent direct contact between the gas generator and the gas bag fabric during inflation. The gas can thereby flow into the gas bag both through openings at the front of the cover and at the side of the cover. This cover is not suitable for the particular flame protection of darts in the gas bag.
The objective of the invention is to reduce the thermal stresses on the seams, and more particularly on the darts in gas bags.
A flame protection device for gas bags in airbag modules which use a gas generator is provided for gas bags with at least one dart. The flame protection device can be folded along with the gas bag. According to the invention, at least one part which directs or diverts the gas jet of the gas generator is provided as a flame protection device. It is arranged and formed so that the gas flows between the darts at least approximately in the direction of these darts.
With this flame protection device, flame protection is achieved in that the hot gases do not hit the seams but are diverted and run in the direction of the seams. A special protection of the seams is thereby not necessary.
In a preferred embodiment, it is proposed that the diverting part is formed as a tubular hose which has at least one outlet opening for the gases leaving the gas generator. This embodiment is suitable for protecting differently aligned darts.
In one embodiment, it is proposed that the darts run at least approximately parallel to each other so that the tubular hose runs transversely relative to the darts and has at least one gas outlet opening between the darts. With this configuration, after emerging from the gas generator the gas is thus first directed in the direction of the darts, but exits through the relevant gas outlet opening between the darts at least approximately in a direction corresponding to the course of the darts. The thermal strain on the darts is thus greatly reduced.
With this arrangement, the tubular hose can be mounted at one end of the darts. In this case, the hose has gas outlet openings on one side. The tubular hose can however also run along both sides of the darts. In this case, the tubular hose therefore has gas outlet openings on opposite sides.
Another possibility exists where the tubular hose runs between the darts in the direction thereof and has at least one gas outlet opening on the end side.
The tubular hose used in the preferred embodiment can be formed in a different way. Thus, in a first embodiment the tubular hose can be formed between a fabric layer folded in the longitudinal direction so that the superposed free edges are connected to the outer edge of the gas bag. In the case of a gas bag consisting of an upper part and a lower part, the edges of the fabric layer of the tubular hose are stitched to the edges of the upper and lower parts. With this embodiment the tubular hose thus arises with the gas bag.
Furthermore, the tubular hose can be made so that one edge of a separate fabric layer is connected to the circumferential seam of the gas bag and the edge opposite this edge is connected to a section of an upper or lower part of the gas bag, or so that one edge of a fabric layer is connected to the upper part and the opposite edge is connected to the lower part.
The tubular hose can also be formed from a section of the gas bag so that an inverted area is provided in the gas bag and has a common edge seam with the gas bag.
Finally a separate tubular hose can also be provided which is connected to the gas bag on at least one side.